Ball check valves are very popular types of check valves for use in liquid flow lines. The popularity of ball check valves stems from their relative simplicity of design and their relative inexpense of manufacture.
A problem, however, arises in the use of ball check valves regarding the fact that ball check valves have a tendency to rattle, as illustrated in FIG. 1. Such rattling stems from turbulence within the liquid flowing through the valve. Such turbulence causes the ball to rattle within the valve housing.
Several attempts have been made to minimize rattling within ball check valves. One such method is illustrated in FIG. 2. In this method, the clearance between the ball and the downstream portion of the valve body is substantially reduced. Such reduction in the clearance between the ball and the body of the valve causes additional friction between the fluid, the valve ball and the valve body. Such friction tends to drag the ball downstream and hold it firmly against the downstream end of the valve body. Although this method is relatively effective in minimizing rattle, it suffers from the disadvantage that the additional friction dissipates the kinetic energy of the flowing liquid, thereby increasing pressure drop across the valve.
A second method of reducing rattling in ball check valves is illustrated in FIG. 3. In this second method, the upstream portion of the valve body is considerably shortened. Thus, the incoming liquid impinges with enhanced force against the ball over a relatively short distance. The ball is thereby physically forced downstream up against the downstream end of the valve body. Unfortunately, this second method also results in a decrease in the kinetic energy of the liquid flowing through the valve and therefore also increases the pressure drop across the valve.
Accordingly, there is a need for a ball check valve which substantially minimizes rattling while avoiding the aforementioned problems in the prior art.